Several researchers funded by the NIAID Human Immunology Project Consortium (HIPC) are conducting detailed studies of the human immune response to influenza vaccination, to understand the ways in which protective antibodies are induced after immunization. Recently, researchers at the Food and Drug Administration (FDA) developed new and highly sophisticated methods to measure the amounts and types of influenza-reactive antibodies that are produced. Thus, the collaboration between HIPC and FDA researchers combines cutting-edge technology with well-defined samples from human vaccinees. This information will support the creation of improved vaccines, which are needed to protect the most vulnerable populations such as the very young, the elderly, and those with immune systems that are weakened due to therapies due to underlying chronic diseases.